One of the primary problems that has limited development of rechargeable batteries has been the formation of dendrite lithium on the negative electrode. This has led to two difficulties:
(a) Low cycling efficiency has resulted from lithium dendrite becoming electrically isolated and high corrosion rate due to high surface area of the lithium dendrites.
(b) Lithium dendrites have grown through the separator causing an internal short circuit. The resulting high currents have heated the battery to the point that the highly reactive lithium reacts explosively with the electrolyte and cathode materials. This safety hazard has been a serious drawback of rechargeable lithium batteries and even some primary lithium systems where lithium dendrites form on overcharge.
The development of rechargeable lithium batteries such as Li/LiAlCl.sub.4 --3SO.sub.2 /C or rechargeable cells such as Li/TiS.sub.2 organic solvents and salts such as LiBr or LiI has at least in principle minimized the lithium cycling efficiency problem. Soluble overcharge products formed at the positive electrode have reacted with the dendrites to reform the electrolyte salt which has gone back into solution. Therefore, by sufficiently overcharging the cell, it should be possible to retrieve isolated lithium dendrites and in some cases lithium corrosion products such that no anode material is lost during repeated cycling. Unfortunately, reaction of overcharge products with lithium dendrites has usually not been rapid enough to prevent cell shorting. Furthermore, even the development of finely porous, microporous and solvent swellable membranes for lithium secondary cells has not been able to completely eliminate the internal shorting problem.